This invention relates to an engine room-cooling control system which is adapted to control temperature within an engine room in an improved manner by means of cooling means provided in the engine room.
Conventionally, as a system for cooling the engine room of an automotive vehicle, a ventilating system has been proposed by Japanese Utility Model Publication (Kokoku) No. 55-34101, which comprises an electric fan which is mounted on a bonnet, etc. for auxiliary ventilating purposes and is driven to operate and stop depending on the engine room temperature or the engine coolant temperature, so that the engine room temperature is maintained at such a suitable temperature as to prevent overheating of the engine, vapor locking of fuel, and other thermal damage to the engine.
However, the proposed control system is adapted to merely operate and stop the electric fan depending on whether the temperature within the engine room or the temperature of the engine per se is higher than a predetermined value. As a result, it is difficult to control the electric fan to operate just to a degree sufficient to exactly bring the engine room temperature to a required value. For instance, the electric fan may be driven to an excessive degree for prevention of thermal damage, which may result in excessive exhaustion of a battery which supplies power to the electric fan.
Further, cooling control systems have been conventionally known, which comprise a second control system provided in addition to a control system for controlling the engine per se, the second control system controlling the operation of a cooling device for cooling the engine, in response to outputs from sensors for detecting operating conditions of the engine, so as to cool the engine to a sufficient degree while preventing an excessive rise in the engine temperature, to thereby secure proper operation of the engine as well as to prevent the engine and its auxiliary equipments from being shorten in life. One of such cooling control systems have been proposed by Japanese Provisional Patent Publication (Kokai) No. 57-191415, which comprises an electric fan which is operable in the event of failure of the above-mentioned sensors, drive means for driving a water pump as the cooling device, or the control system, to deliver cooling air to the engine so as to prevent an excessive rise in the temperature thereof.
However, the proposed cooling control system essentially requires the provision of an exclusive electric fan for use only in the event of failure of the sensors, etc., and thus is disadvantageous in that the system is high in manufacturing cost, and large in size.
Furthermore, in the above-mentioned conventional cooling control systems the water pump and the electric fan are disposed to cool the engine alone. Therefore, if they are used in an engine equipped with a turbocharger, for example, they are unable to prevent an excessive rise in the temperature of the turbocharger. Besides, the turbocharger forms one of main heat sources within the engine room, so that an excessive rise in the temperature of the engine due to increased temperature of the turbocharger cannot be prevented, thereby being unable to secure proper operation of the engine and a sufficient life of the engine.
Still further, in the conventional cooling control systems the electric fan is disposed to deliver cooling air directly to the engine to cool same, but not to deliver cooling air to a radiator in the engine room to cool same. Therefore, the radiator can be cooled to an insufficient degree, causing an excessive rise in the engine temperature, and hence leading to the above-mentioned disadvantages.